Perhaps it's because (generally speaking, of course) Americans have kept a far firmer grasp on their cultural identity than we have
When I think of American pop culture vs. British (and other European) pop culture I get the impression that it was the British who tried to keep that firm grasp on their cultural identity, while the American approach of doing so feels less intentional. They had, and still have, so much going on in their own huge country that they don't need any cultural import.
Why promote a single by a relatively unknown Swedish band like ABBA when they've got thousands of singles by US established artists to promote? Was it anti-Euro snobbery or simply a matter of logistics and not wasting time and effort on something that may or may not become a hit?
Interestingly, something similar happened in Europe in the 90s decade when house music started to dominate the European charts. The Euro-made supply of said music was so overwhelming that it almost seemed impossible, not to mention unnecessary, to squeeze in the American dance tunes that also had a very different sound to the Euro tunes.
This changed at the end of the decade with the increasing popularity of modern R&B music* and Latin-American productions, which resulted in Europeans mimicking the American sound.
Although it should be noted that some of the biggest US hits of that time had European songwriters and producers behind it. What didn't work for ABBA certainly worked for Britney Spears.
*(I wonder how much of this mirrors the success of Sugarhill Gang's "Rapper's Delight" at the time that 1970s disco music as we knew it in Europe started to change, although I'm sure that the popularity of the 80s electronic sound played the biggest part in it).
Generally speaking, the attitude towards foreign TV productions in Holland (I'd rather not speak for other European countries) has always been very impartial. Similar to our music charts, everything and everyone had an equal opportunity to become a hit. I like that, it makes things a little bit more adventurous.
In addition to the hit singles and tv hit shows that were popular in both/either US and UK, we got the imports from Germany, France and Italy. The most popular foreign TV show of the 80s was not
Dallas but The
Flying Doctors, and probably the German crime show
Derrick, too.
But most of the easy-to-digest family entertainment mainly targeted at a younger audience were American productions (The A-Team, Knight Rider, Dukes Of Hazzard etc.)
I'd be hard-pressed to name a similar TV show from the UK or elsewhere that was equally successful (Dick Turpin?)
On the other hand, most of the sitcoms we got in the 1970s were British. We had
All In The Family and
Mork & Mindy, but that was it, I think.